President Donald Trump suggested challenging licenses for NBC and other broadcast news networks following reports by NBC News that Trump wanted to make the US nuclear stockpile nearly 10 times larger.
The report also said his secretary of state Rex Tillerson had called him a ''moron'' after a discussion of the US nuclear arsenal.
''With all of the Fake News coming out of NBC and the Networks, at what point is it appropriate to challenge their License? Bad for country!'' Trump, a Republican, wrote in a post on Twitter on Wednesday.
He returned to the topic the same night, tweeting, "Network news has become so partisan, distorted and fake that licenses must be challenged and, if appropriate, revoked. Not fair to public!"
Trump and his supporters have repeatedly used the term ''fake news'' to cast doubt on media reports critical of his administration, often without providing any evidence to show that the reports were untrue.
Trump kept up his criticism of the media in an appearance with Canadian Prime Minister Justin Trudeau, saying, ''It is frankly disgusting the press is able to write whatever it wants to write.''
But experts aren't too worried, as any move to challenge media companies' licenses would face significant hurdles.
The network itself doesn't need a license to operate, but individual stations do. NBC owns several stations in major cities. Stations owned by other companies such as Tribune and Cox carry NBC's news shows and other programs elsewhere.
The Federal Communications Commission, an independent federal agency, does not license broadcast networks, but issues them to individual broadcast stations that are renewed on a staggered basis for eight-year periods.
Comcast Corp, which owns NBC Universal, also owns 11 broadcast stations, including outlets in New York, Washington, Los Angeles, San Francisco, Boston, Dallas and Chicago.
A Comcast spokeswoman referred questions from Reuters to NBC, which did not immediately respond. ABC, owned by Walt Disney Co, declined to comment. NBC spokeswoman Hilary Smith also had no comment for AP, and nor did the spokesperson for FCC chairman Ajit Pai.
Shares in media companies fell, potentially reflecting concerns the war of words could worsen. Comcast was down 0.8 per cent, while Disney shed 1.4 per cent, CBS Corp fell 1.2 per cent and Twenty-First Century Fox slid 2.8 per cent.
Recon Analytics analyst Roger Entner called the market response a ''short-term irrational knee-jerk reaction'', telling Reuters Trump faced essentially insurmountable hurdles to getting licenses pulled.
Gordon Smith, the chief executive of the National Association of Broadcasters, defended the media's free speech rights. ''It is contrary to this fundamental right for any government official to threaten the revocation of an FCC license simply because of a disagreement with the reporting of a journalist,'' Smith said in a statement.
These days, license renewal is fairly routine. A station could be deemed unfit and have its license stripped if it were telling lies and spreading fake news, as Trump claims. But Harold Feld of the consumer group Public Knowledge says that's tough to prove.
Feld told AP he could recall just two instances in the past 20 years when there has been a renewal challenge. One involved an owner of radio stations who was convicted for child molestation, and the other when someone died as part of a radio station's contest. Both lost their licenses.
Senator Ed Markey wrote FCC chairman Pai on Wednesday asking him to ''withstand any urges from President Trump to harm the news media and infringe upon the First Amendment,'' a reference to the U.S. Constitution's free speech and press freedom guarantee.
Democratic US Representative Frank Pallone said Trump ''seemed to threaten broadcasters' licenses only because he disagreed with their reporting. This threat alone could intimidate the press and lead to skewed and unfair reporting.''
FCC Commissioner Jessica Rosenworcel responded to Trump by tweeting a link to an FCC fact sheet. ''Not how it works,'' she said on Twitter.
Trump on Saturday also suggested he should get ''equal time'' because of what he described as late-night television hosts' ''anti-Trump'' material. But the FCC's equal time rules apply in limited cases to air time for political candidates and not to criticism of elected leaders.